Twitter Application-only authentication in Salesforce Apex

Hello all,

Today I will be posting an example on how to implement the Twitter Application-only authentication using Salesforce Apex.

Overview

The Twitter Application-only authentication is used when no user sign-in with Twitter is required.
When using this type of authentication, we are allowed to call limited Twitter functionalities, namely :

Pull user timelines;

Access friends and followers of any account;

Access lists resources;

Search in tweets;

Retrieve any user information;

In our example, we will be implementing the Authentication flow described in Twitter Application-only authentication which involves two HTTP requests.

Code

 public TwitterContr(){  
      HttpRequest req = new HttpRequest();  
      req.setMethod('POST');  
      req.setEndpoint('https://api.twitter.com/oauth2/token');  
        
      //// Step 1: Encode consumer key and secret  
        
      String consumerKey = 'xvz1evFS4wEEPTGEFPHBog';  
      String consumerSecret = 'L8qq9PZyRg6ieKGEKhZolGC0vJWLw8iEJ88DRdyOg';  
        
      Blob headerValue = Blob.valueOf(consumerKey + ':' + consumerSecret);  
      String authorizationHeader = 'Basic ' + EncodingUtil.base64Encode(headerValue);  
     
      //// Step 2: Obtain a bearer token  
             
      req.setHeader('Authorization', authorizationHeader);  
      req.setHeader('Content-Type','application/x-www-form-urlencoded;charset=UTF-8');  
      req.setBody('grant_type=client_credentials');  
     
      // Create a new http object to send the request object  
      // A response object is generated as a result of the request  
      // the server will respond with a JSON-encoded payload  
     
      Http http = new Http();  
      HTTPResponse res = http.send(req);  
      
      String jsonStr = res.getbody();  
      JSONParser parser = JSON.createParser(jsonStr);  
        
      // extract access token from JSON response  
      string accessToken;  
      while (parser.nextToken() != null) {  
           if ((parser.getCurrentToken() == JSONToken.FIELD_NAME) && (parser.getText() == 'access_token')) {  
                // Get the value.  
                parser.nextToken();  
                accessToken = parser.getText();  
           }  
      }  
     
      // access token can now be used to perform other requests  
      //// Step 3: Authenticate API requests with the bearer/access token  
        
      // e.g. searching for tweets   
        
      HttpRequest req1 = new HttpRequest();  
      req1.setMethod('GET');  
      req1.setEndpoint('https://api.twitter.com/1.1/search/tweets.json?q=%23freebandnames');  
     
      String authorizationHeader1 = 'Bearer ' + accessToken;  
      req1.setHeader('Authorization', authorizationHeader1);  
     
      Http http1 = new Http();  
      HTTPResponse searchResponse = http.send(req1);  
      system.debug('## body1 : ' + searchResponse.getBody());  
 }  

Cheers!!